couple of options -- 1) find a few good ones that work and just recycle them. People have to see a message multiple times before it sinks in.

2) try something catchy, whether it ties directly to your business or not: "got stuff?" or "smiles served daily". A chiropractor might say "we've got your back"; not sure what the storage equivalent is, but that is an idea.

We use our sign for cute catchy sayings. They don't have anything to do with the business but they sure get the attention. We also will use short thought provoking quotes. We get alot of positive feedback from the community. They actually look forward to seeing the next "message".
A couple of examples 'Praise loudly - Blame softly' or 'Don't count your years - Make your years count'.
We have a folder with all kinds of saying that we have collected. Now we have the family involved. If they see a good one they send it to us. Just another way to make your place get noticed!!

One of our competitors (well actually, other than us and one or two others, own all the storage facilities in town) flash "Price War!!! 1/2 off 1st month" on their LED, so we put "Tired of wars? Get peace of mind when you store here" on our sign.

Love the "tired of wars!" That will go very far! I also am a fan of trivia type info, or the cute sayings. My motto is create warm fuzzies! I would much rather do business with a company that makes me smile & feel good. It gives me the idea they are real caring people! Boxes 20% off or Free Rental Truck- just doesn't do that for me! Not that I am like the general population-- have been told that many times!! HA HA !!

i love the motto, quotes idea also - maybe a different one on each side - not sure what they (AM) will say about it - but am going to give it a try - if i can i will post some pics or at least post what i decided on - thank you all so much for helping open my eyes to other possibilities -

i also like the 'tired of wars' - but we are really the only one around here - kind of sandwiched in between two apartment complexes.

Although it is not a marquee sign, get an "Easy" button from Staples and put it on your counter. It will give the people coming through your door "warm and fuzzies". People find it impossible to not laugh and/or smile after they hit the button.